Poor delivery service

I had a delivery due to me around the end of June and pargo was entrusted with delivering it to me. Without prior communication or notification either by text or email my parcel was delivered to a certain address and up until now its whereabouts are unknown. The people at that address claim to not know of such a delivery and I've since asked Pargo to send me a copy of the delivery receipt to see who signed for it so I know who to look for when I go back to that address but they have been of no assistance. Instead they send me an incomplete screen shot of a cut of signature and now they are not responding to my emails.

Who is to blame in such an case? Pargo never called me to confirm delivery address, they didn't notify me when they delivered the parcel and now they're not bothered to assist me in ensuring I get my parcel. Now my business is running a loss because they lost my products.